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  <div class="section" id="data-marshalling-support">
<span id="marshalling-utils"></span><h1>数据 marshal 操作支持<a class="headerlink" href="#data-marshalling-support" title="永久链接至标题">¶</a></h1>
<p>这些例程允许 C 代码处理与 <a class="reference internal" href="../library/marshal.html#module-marshal" title="marshal: Convert Python objects to streams of bytes and back (with different constraints)."><code class="xref py py-mod docutils literal notranslate"><span class="pre">marshal</span></code></a> 模块所用相同数据格式的序列化对象。 其中有些函数可用来将数据写入这种序列化格式，另一些函数则可用来读取并恢复数据。 用于存储 marshal 数据的文件必须以二进制模式打开。</p>
<p>数字值在存储时会将最低位字节放在开头。</p>
<p>此模块支持两种数据格式版本：第 0 版为历史版本，第 1 版本会在文件和反向 marshal 操作时共享固化的字符串。 第 2 版本会对浮点数使用二进制格式。 <code class="docutils literal notranslate"><span class="pre">Py_MARSHAL_VERSION</span></code> 指明了当前文件的格式（当前取值为 2）。</p>
<dl class="function">
<dt id="c.PyMarshal_WriteLongToFile">
void <code class="sig-name descname">PyMarshal_WriteLongToFile</code><span class="sig-paren">(</span>long<em> value</em>, FILE<em> *file</em>, int<em> version</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyMarshal_WriteLongToFile" title="永久链接至目标">¶</a></dt>
<dd><p>将一个 <code class="xref c c-type docutils literal notranslate"><span class="pre">long</span></code> 整数 <em>value</em> 以 marshal 格式写入 <em>file</em>。 这将只写入 <em>value</em> 最低的 32 位；无论本机 <code class="xref c c-type docutils literal notranslate"><span class="pre">long</span></code> 类型的长度如何。 <em>version</em> 指明文件格式的版本。</p>
</dd></dl>

<dl class="function">
<dt id="c.PyMarshal_WriteObjectToFile">
void <code class="sig-name descname">PyMarshal_WriteObjectToFile</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *value</em>, FILE<em> *file</em>, int<em> version</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyMarshal_WriteObjectToFile" title="永久链接至目标">¶</a></dt>
<dd><p>将一个 Python 对象 <em>value</em> 以 marshal 格式写入 <em>file</em>。 <em>version</em> 指明文件格式的版本。</p>
</dd></dl>

<dl class="function">
<dt id="c.PyMarshal_WriteObjectToString">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a>* <code class="sig-name descname">PyMarshal_WriteObjectToString</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *value</em>, int<em> version</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyMarshal_WriteObjectToString" title="永久链接至目标">¶</a></dt>
<dd><em class="refcount">Return value: New reference.</em><p>返回一个包含 <em>value</em> 的 marshal 表示形式的字节串对象。 <em>version</em> 指明文件格式的版本。</p>
</dd></dl>

<p>以下函数允许读取并恢复存储为 marshal 格式的值。</p>
<dl class="function">
<dt id="c.PyMarshal_ReadLongFromFile">
long <code class="sig-name descname">PyMarshal_ReadLongFromFile</code><span class="sig-paren">(</span>FILE<em> *file</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyMarshal_ReadLongFromFile" title="永久链接至目标">¶</a></dt>
<dd><p>从打开用于读取的 <code class="xref c c-type docutils literal notranslate"><span class="pre">FILE*</span></code> 的对应数据流返回一个 C <code class="xref c c-type docutils literal notranslate"><span class="pre">long</span></code>。 使用此函数只能读取 32 位的值，无论本机 <code class="xref c c-type docutils literal notranslate"><span class="pre">long</span></code> 类型的长度如何。</p>
<p>发生错误时，将设置适当的异常 (<a class="reference internal" href="../library/exceptions.html#EOFError" title="EOFError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">EOFError</span></code></a>) 并返回 <code class="docutils literal notranslate"><span class="pre">-1</span></code>。</p>
</dd></dl>

<dl class="function">
<dt id="c.PyMarshal_ReadShortFromFile">
int <code class="sig-name descname">PyMarshal_ReadShortFromFile</code><span class="sig-paren">(</span>FILE<em> *file</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyMarshal_ReadShortFromFile" title="永久链接至目标">¶</a></dt>
<dd><p>从打开用于读取的 <code class="xref c c-type docutils literal notranslate"><span class="pre">FILE*</span></code> 的对应数据流返回一个 C <code class="xref c c-type docutils literal notranslate"><span class="pre">short</span></code>。 使用此函数只能读取 16 位的值，无论本机 <code class="xref c c-type docutils literal notranslate"><span class="pre">short</span></code> 的长度如何。</p>
<p>发生错误时，将设置适当的异常 (<a class="reference internal" href="../library/exceptions.html#EOFError" title="EOFError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">EOFError</span></code></a>) 并返回 <code class="docutils literal notranslate"><span class="pre">-1</span></code>。</p>
</dd></dl>

<dl class="function">
<dt id="c.PyMarshal_ReadObjectFromFile">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a>* <code class="sig-name descname">PyMarshal_ReadObjectFromFile</code><span class="sig-paren">(</span>FILE<em> *file</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyMarshal_ReadObjectFromFile" title="永久链接至目标">¶</a></dt>
<dd><em class="refcount">Return value: New reference.</em><p>从打开用于读取的 <code class="xref c c-type docutils literal notranslate"><span class="pre">FILE*</span></code> 的对应数据流返回一个 Python 对象。</p>
<p>发生错误时，将设置适当的异常 (<a class="reference internal" href="../library/exceptions.html#EOFError" title="EOFError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">EOFError</span></code></a>, <a class="reference internal" href="../library/exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a> 或 <a class="reference internal" href="../library/exceptions.html#TypeError" title="TypeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">TypeError</span></code></a>) 并返回 <code class="docutils literal notranslate"><span class="pre">NULL</span></code>。</p>
</dd></dl>

<dl class="function">
<dt id="c.PyMarshal_ReadLastObjectFromFile">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a>* <code class="sig-name descname">PyMarshal_ReadLastObjectFromFile</code><span class="sig-paren">(</span>FILE<em> *file</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyMarshal_ReadLastObjectFromFile" title="永久链接至目标">¶</a></dt>
<dd><em class="refcount">Return value: New reference.</em><p>从打开用于读取的 <code class="xref c c-type docutils literal notranslate"><span class="pre">FILE*</span></code> 的对应数据流返回一个 Python 对象。 不同于 <a class="reference internal" href="#c.PyMarshal_ReadObjectFromFile" title="PyMarshal_ReadObjectFromFile"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyMarshal_ReadObjectFromFile()</span></code></a>，此函数假定将不再从该文件读取更多的对象，允许其将文件数据积极地载入内存，以便反序列化过程可以在内存中的数据上操作而不是每次从文件读取一个字节。 只有当你确定不会再从文件读取任何内容时方可使用此方式。</p>
<p>发生错误时，将设置适当的异常 (<a class="reference internal" href="../library/exceptions.html#EOFError" title="EOFError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">EOFError</span></code></a>, <a class="reference internal" href="../library/exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a> 或 <a class="reference internal" href="../library/exceptions.html#TypeError" title="TypeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">TypeError</span></code></a>) 并返回 <code class="docutils literal notranslate"><span class="pre">NULL</span></code>。</p>
</dd></dl>

<dl class="function">
<dt id="c.PyMarshal_ReadObjectFromString">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a>* <code class="sig-name descname">PyMarshal_ReadObjectFromString</code><span class="sig-paren">(</span>const char<em> *data</em>, Py_ssize_t<em> len</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyMarshal_ReadObjectFromString" title="永久链接至目标">¶</a></dt>
<dd><em class="refcount">Return value: New reference.</em><p>从包含指向 <em>data</em> 的 <em>len</em> 个字节的字节缓冲区对应的数据流返回一个 Python 对象。</p>
<p>发生错误时，将设置适当的异常 (<a class="reference internal" href="../library/exceptions.html#EOFError" title="EOFError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">EOFError</span></code></a>, <a class="reference internal" href="../library/exceptions.html#ValueError" title="ValueError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">ValueError</span></code></a> 或 <a class="reference internal" href="../library/exceptions.html#TypeError" title="TypeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">TypeError</span></code></a>) 并返回 <code class="docutils literal notranslate"><span class="pre">NULL</span></code>。</p>
</dd></dl>

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